The class of linear alternating copolymers of carbon monoxide and at least one mono-olefinically unsaturated hydrocarbon is now well known in the art. Such polymers, produced for example by the processes of van Broekhoven et al, U.S. Pat. Nos. 4,843,144 and 4,880,903, are represented by the repeating formula ##STR1## wherein A is derived from at least one mono-ethylenical unsaturated hydrocarbon polymerized through the ethylenic unsaturation thereof. The scope of the production of such linear alternating polymers is extensive but the polymerization is preferably conducted in the presence of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, an anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus, nitrogen or sulfur. Although a wide variety of bidentate ligands are useful in the polymerization process, the preferred ligands are bidentate ligands of phosphorus containing aromatic monovalent phosphorus substituents. Particularly good results are often obtained using catalyst compositions formed from 1,3-bis(diphenylphosphino)propane or 1,3-bis[di(2-methoxyphenyl)phosphino]propane.
Somewhat more difficult considerations apply to the production of the alternating polymers when part or all of the mono-olefin is replaced with a diolefin. In U.S. Pat. No. 4,940,777 there is described a process of producing copolymers of carbon monoxide and an .alpha.-.beta.-diolefin. The process utilizes a catalyst composition as described above wherein the bidentate ligand is a bidentate ligand of nitrogen such as 2,2'-bipyridine. Catalyst compositions formed from a compound of palladium, the anion of a strong non-hydrohalogenic acid and tetraaryl phosphorus bidentate ligands are useful in the production of linear alternating terpolymers of carbon monoxide, .alpha.-monoolefin and either conjugated or non-conjugated diolefins. See, for example, U.S. Pat. No. 4,904,759 or U.S. Pat. No. 4,940,775. It would be of advantage, however, to provide a process for the production of alternating copolymers of carbon monoxide and non-conjugated diolefins.